Catheter

ABSTRACT

Catheter ( 1 ), comprising a catheter body ( 2 ), the inner volume of which forms a first catheter channel ( 4 ), which serves to accommodate a guide wire ( 15 ) during the introduction of the catheter into the body of a patient, with at least one separating wall ( 5 ), arranged therewithin, which divides off at least one further catheter chamber ( 6 ) in the interior. According to the invention, a catheter chamber with the largest possible cross-sectional area with a given external diameter may be provided, whereby the catheter body ( 2 ) has a tubular outer wall ( 3 ), the cross-sectional area (F 2 ) of the further catheter chamber ( 6 ) is smaller than the cross-sectional area (F 1 ) of the first catheter chamber ( 4 ) and the further catheter chamber ( 6 ) is arranged such as to comprise a wall section which is part of the tubular outer wall ( 3 ).

The invention relates to a catheter having a catheter body, the interiorof which forms a first catheter lumen, which serves to accommodate aguide wire during the introduction of the catheter into the body of apatient, having at least one partition disposed in the interior, whichdivides off at least one further catheter lumen in the interior.

Catheters having two or more lumens are used in surgical interventionsand in intensive care medicine, in order, for example, to measuretemperature and pressure in various body regions, to take samples ofliquid for analysis purposes, or to supply liquids.

Catheters for invasive measurement of temperature and blood pressurehave a round lumen for measuring pressure, supplying and removingliquids, as well as a D-shaped, half-moon-shaped, or round lumen foraccommodating a thermistor for the invasive temperature measurement.

The known catheters of this type cannot be used for small blood vessels,because of their diameter dimension. When their outside diameter isreduced, the flow resistance increases markedly, so that the supply andremoval of liquid and even the pressure measurement are significantlyimpaired. In particular, if the catheter is equipped with acomparatively long catheter tube, the great flow resistance becomesnoticeable to a disruptive degree.

The invention is based on the task of creating a catheter of the typestated initially, which is characterized by a small outside diameterand, at the same time, a low flow resistance in at least one lumen.

This task is accomplished, in the case of a catheter of the type statedinitially, in that the catheter body has a tubular outer wall and thatthe cross-sectional area of the further catheter lumen is smaller thanthe cross-sectional area of the first catheter lumen, and the furthercatheter lumen is disposed in such a manner that it has a wall sectionthat is part of the tubular outer wall.

By means of this method of arrangement, according to the invention, thecross-sectional area of the catheter tube is utilized in optimal manner,so that the larger catheter lumen, in any case, has such across-sectional area that its flow resistance lies within limits thatpermit problem-free pressure measurement with a low response delay, evenwith extremely small outside diameters. The catheter is suitable forinvasive temperature and blood pressure measurements (e.g. in connectionwith the determination of the heart/time volume, wherein the catheter isintroduced into an artery, for example), even in children. Despite theessentially eccentric placement of the further catheter lumen, thecatheter demonstrates sufficient stiffness so as to allow handling ofthe catheter in the usual manner. The catheter according to theinvention can also be provided with a longer catheter body, incomparison with the state of the art, without causing problems in thepressure measurement, and without exceeding the diameter values ofconventional catheters.

Surprisingly, it has been shown that despite the cross-sectional area ofthe first catheter lumen, which deviates from the circular shape, it isexcellently suited for accommodating the guide wire, and that thecatheter can be pushed into a blood vessel over the guide wire, withoutproblems, for example according to the Seldinger technique, until it hasreached its final position. The subsequent “drawing” of the guide wirealso proceeds without problems, and in particular, no jamming or wedgingof the guide wire in the first catheter lumen occurs, and the latter issubsequently used, for example, to measure blood pressure or to supplyliquid substances, in accordance with its intended purpose.

In an advantageous embodiment, the cross-sectional area of the firstcatheter lumen and the cross-sectional area of the further catheterlumen have a common axis of symmetry in the cross-sectional plane, andthe quotient of the cross-sectional area of the first catheter lumen andthe cross-sectional area of the further catheter lumen is greater thanthe square of the quotients of the width of the first catheter lumen,measured along the common axis of symmetry, and the width of the furthercatheter lumen, measured along the common axis of symmetry. If thisregulation for dimensions is adhered to, it is assured that thecross-sectional area of the first catheter lumen has an optimal size.

It is furthermore advantageous if the partition runs in arc shape overat least one section of the same. A partition configured in this mannermolds itself to the shape of the further lumen and thereby permits thebest possible utilization of the available space, whereby it isparticularly advantageous if the arc-shaped partition has a convex sidethat faces the first catheter lumen, and a concave side that faces thefurther catheter lumen.

The choice of an approximately round shape for the further catheterlumen has proven itself to be particularly suitable not only from theaspect of an optimal division of space, but also from the aspect ofachieving a sufficient bending stiffness of the catheter body.

The further catheter lumen is particularly suitable for accommodating atemperature sensor that can be disposed in the region of the cathetertip, and which can fill the available cross-sectional area preferably byfour-fifths, in order to achieve a play that allows easy insertion, oralso completely.

If polyurethane, preferably having a Shore hardness between 60D and 85D,is used as the material for the catheter, it is found that on the onehand, the catheter demonstrates satisfactory stiffness, and on the otherhand, reliable anti-lock sliding of the catheter relative to the guidewire disposed in the first catheter lumen is also possible.

With regard to reliable sliding of the guide wire, it has proven to beadvantageous if the guide wire has a diameter that amounts to 65% to 95%of the distance between the partition and the outer wall.

The invention will be explained in greater detail below, on the basis ofan exemplary embodiment shown schematically in FIGS. 1 and 2.

FIG. 1 shows an external view of the catheter according to theinvention,

FIG. 2 shows a cross-section of the catheter along the section lineII-II in FIG. 1, on an enlarged scale.

The thermodilution catheter shown in FIG. 1, for continuous measurementof temperature and pressure in a blood vessel (e.g. femoral artery) hasa catheter body 2 that extends from a Y connector piece 10 to thecatheter tip 9. On the side of the Y connector piece 10 opposite thecatheter body, the former is connected with a pressure tube 11 as wellas with an electrical line 12. A plug 13 is disposed at the end of theelectrical line, making a connection to an evaluation unit (not shown)possible. A tube coupling piece 14 is located at the end of the pressuretube 11.

The structure of the catheter body 2 according to the invention can beseen in the cross-sectional drawing of FIG. 2.

The catheter body 2 has a tubular outer wall 3 having an approximatelyuniform wall thickness. A first catheter lumen 4 is configured in theinterior of the catheter body 2, which lumen is sickle-shaped incross-section, as can be seen in the figure. The interior contains apartition 5 that divides off a further catheter lumen 6, which isapproximately circular, as can be seen in the figure. Thecross-sectional area F1 of the sickle-shaped first catheter lumen 4 isgreater than the cross-sectional area F2 of the further catheter lumen6.

The further catheter lumen 6 is disposed eccentrically, in such a mannerthat it has a wall section 7 in common with the outer wall 3. Theremaining wall of the further catheter lumen 6, by means of which thetwo catheter lumens 4 and 6 are separated, i.e. the partition 5, isarc-shaped. The concave side of the arc-shaped partition 5 faces the(round) further catheter lumen 6, the convex side faces the(sickle-shaped) first catheter lumen 4. In the exemplary embodimentdescribed, the further catheter lumen 6 serves to accommodate atemperature sensor. The further catheter lumen 6 can also be intended toaccommodate an optical fiber sensor (not shown). Depending on theapplication case, the further catheter lumen 6 is sealed or open at thecatheter tip 9.

By means of the structure described, solid material regions are avoided,to the greatest possible extent, and thereby the collapse regions thatoften occur after extrusion, because of such material accumulations, arealso avoided.

In the case of the division of the interior of the catheter according tothe invention, as described, a comparatively large cross-sectional areais imparted to the first lumen, so that the flow resistance can be keptlow, if, for example, blood flows through this catheter lumen. Thisallows a reduction of the catheter diameter as compared withconventional catheters, or, alternatively, the use of significantlylonger catheter bodies with the same diameter.

The dimensions of the two catheter lumens and the arrangement of thecatheter lumens are selected in such a manner that the cross-sectionalarea F1 of the first catheter lumen 4 and the cross-sectional area F2 ofthe further catheter lumen 6 have a common axis of symmetry in thecross-sectional plane, and the quotient of the cross-sectional area F1of the first catheter lumen 4 and the cross-sectional area F2 of thefurther catheter lumen 6 is greater than the square of the quotients ofthe width D1 of the first catheter lumen 4, measured along the commonaxis of symmetry, and the width D2 of the further catheter lumen 6,measured along the common axis of symmetry. Consequently, the followingapplies:$\frac{F\quad 1}{F\quad 2} > \left( \frac{D\quad 1}{D\quad 2} \right)^{2}$

As is further evident from FIG. 2, a guide wire 15 made of steel islocated in the further catheter lumen 4. The further catheter lumen 4therefore serves as a guide wire lumen during the introduction phase ofthe catheter. As is evident from the figure, the diameter of the guidewire 15 is less than the clear width D1 between the outer wall 3 and thepeak of the arc-shaped partition 5.

1. Catheter (1) having a catheter body (2), the interior of which formsa first catheter lumen (4), which serves to accommodate a guide wire(15) during the introduction of the catheter into the body of a patient,having at least one partition (5) disposed in the interior, whichdivides off at least one further catheter lumen (6) in the interior,wherein the catheter body (2) has a tubular outer wall (3) and thecross-sectional area (F2) of the further catheter lumen (6) is smallerthan the cross-sectional area (F1) of the first catheter lumen (4), andthe further catheter lumen (6) is disposed in such a manner that it hasa wall section (7) that is part of the tubular outer wall (3). 2.Catheter according to claim 1, wherein the cross-sectional area (F1) ofthe first catheter lumen (4) and the cross-sectional area (F2) of thefurther catheter lumen (6) have a common axis of symmetry in thecross-sectional plane, and the quotient of the cross-sectional area (F1)of the first catheter lumen (4) and the cross-sectional area (F2) of thefurther catheter lumen (6) is greater than the square of the quotientsof the width (D1) of the first catheter lumen (4), measured along thecommon axis of symmetry, and the width (D2) of the further catheterlumen (6), measured along the common axis of symmetry.
 3. Catheteraccording to claim 1, wherein the partition (5) runs in arc shape overat least one section of same.
 4. Catheter according to claim 3, whereinthe arc-shaped partition (5) has a convex side that faces the firstcatheter lumen (4), and a concave side that faces the further catheterlumen (6).
 5. Catheter according to claim 1, wherein the cross-sectionalarea (F1) of the first catheter lumen (4) has a rounded sickle shape. 6.Catheter according to claim 1, wherein the cross-sectional area (F2) ofthe further catheter lumen (6) is round.
 7. Catheter according to claim1, wherein a temperature sensor is disposed in the further catheterlumen (6).
 8. Catheter according to claim 7, wherein the temperaturesensor is disposed in the vicinity of the catheter tip (9).
 9. Catheteraccording to claim 6, wherein the cross-sectional area of thetemperature sensor fills the cross-sectional area of the furthercatheter lumen (6) by at least four-fifths.
 10. Catheter according toclaim 7, wherein the cross-sectional area of the temperature sensorfills the cross-sectional area of the further catheter lumen (6)completely.
 11. Catheter according to claim 1, wherein an optical fibersensor is disposed in the further catheter lumen (6).
 12. Catheteraccording to claim 1, wherein the further catheter lumen (6) is open inthe region of the catheter tip.
 13. Catheter according to claim 1,wherein the further catheter lumen (6) is closed in the region of thecatheter tip.
 14. Catheter according to claim 1, wherein the catheterbody is made from plastic having a Shore hardness of 60D to 85D. 15.Catheter according to claim 14, wherein the plastic is polyurethane. 16.Catheter system according to claim 1, having a guide wire (15), whereinthe guide wire (15) has a diameter that amounts to 65% to 95% of thedistance (D1) between the partition (5) and the outer wall (3).